1. Field of the Invention
The field of the present invention is air bag systems to be mounted at a central portion of a steering wheel or at an instrument panel for protecting an occupant from a shock upon a collision of a vehicle, and processes for producing the same.
2. Description of the Prior Art
There are conventionally known air bag systems designed so that when a shock more than a given value due to a collision of a vehicle is sensed, an air bag is inflated by a high pressure gas and developed into a vehicle compartment, thereby protecting an occupant from a secondary collision by a cushioning effect of the air bag. In general, such air bag system is adapted to be mounted at a central portion of a steering wheel or at an instrument panel in order to protect the occupant on a driver's seat or on an assistant's seat.
However, an air bag in such an air bag system is made of a soft material such as a synthetic fiber or the like and hence, it is relatively difficult to shape the inflated air bag into a shape suitable for holding or restraining the occupant. Therefore, in an air bag system of a type generally known, an air bag means is comprised of a main bag and an auxiliary bag, so that the inflated air bags may be shaped into shapes suitable for holding the occupant.
However, the air bag system of the above type requires not only two independent air bags but also two gas generators for inflating the air bags, thereby bringing about an increase in cost accompanied by a complication in structure.
Therefore, an air bag system has been proposed in which a hanging string is stretched as a tension member within an air bag. In such system, the air bag is inflated and developed into a shape suitable for holding an occupant by restraining the inflation of the air bag by a tension acting on the hanging string (for example, see Japanese Utility Model Publication Kokoku No. 11084/86).
In the above air bag system, however, in producing the air bag, a base end of the hanging string has previously been sewn to the air bag, then an opening portion of the air bag is mounted to a mounting base of a container having a gas generator mounted thereto so as to improve the assembling property. Therefore, such air bag system suffers from a problem that when sewing the hanging string to the air bag, it is difficult to do so unless the air bag is once turned inside out. This results in a very inferior workability.